1. Field of the Invention
The present invention relates to an electric light source technology field, and more particularly to an organic electroluminescent device structure and manufacturing for the same.
2. Description of Related Art
Currently, in the illumination and display field, an Organic Light-Emitting Diode (OLED) is widely applied in an illumination product and a display panel because of characteristics of a low starting voltage, thin, self-illumination and so on in order to meet the requirements of low energy consumption, self-illumination, and a surface light source and so on. In the display panel industry, comparing with the conventional Thin Film Transistor-Liquid Crystal Display (TFT-LCD), an OLED device has a very excellent display performance. Specifically, features of self-illumination, simple structure, ultra-thin, fast response, wide viewing angle, low power consumption and can realize flexible display and so on. Therefore, the OLED device has been called as a “dream display”. Besides, the cost of the production equipment is less than the LCD display device so that the OLED device has become a mainstream of the third-generation display in the display technology field. Currently, the OLED device is ready for a mass production. With further research and new technologies continuing to emerge, the OLED device will have a breakthrough development.
As shown in FIG. 1, an OLED device sequentially has an anode 200, an organic light emitting layer 300 and a cathode 400 sequentially disposed on a substrate 100. For a bottom-emitting type OLED device, paths for a light to exit usually are: the organic light emitting layer 300, the anode 200, the substrate 100 and an air. A light emitted by the organic light emitting layer 300 passes through above four paths to reach the air, and enters eyes of a human. The organic light emitting layer 300 is made of a small organic molecule material, and the refractive index is about 1.6-1.7. The anode 200 is made of an indium-tin-oxide (ITO) thin film, and the refractive index is about 1.8. The substrate 100 is a glass substrate, and the refractive index is 1.5. The refractive index of the air is 1.0. Accordingly, when a light enters the air from the organic light emitting layer 300, with reference to FIG. 2, the light is propagated from an optically denser medium (with a higher refractive index) to an optically thinner medium (with a lower refractive index). For example, light is propagated from the ITO anode 200 having the refractive index 1.8 to the glass substrate having the refractive index 1.5. Therefore, a total reflection phenomenon is existed. A light having an incident angle greater than a critical angle cannot reach the glass substrate because of the total reflection phenomenon. The light which cannot reach the glass substrate will be absorbed internally and lost. Currently, a conventional OLED device only has a light emitting efficiency about 17%, and most of the light is lost because of the total reflection at the interfaces.
A high flexible PEDOT:PSS (Poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate)) thin film using as an organic transparent conductive film coating has been paid attention in the material field. Because the property of the PEDOT:PSS solution, a common wet coating method can be used for manufacturing the PEDOT:PSS thin film. Comparing with an Indium-Tin-Oxide (ITO) film, required equipment is greatly reduced. Besides, the PEDOT:PSS thin film has been applied at the antistatic coating layer so that relative technology is mature.